Bluetooth Low Energy (BLE) forms part of the Bluetooth V4.0 specification that has been ratified by the Bluetooth SIG since June 2010. But, in the last 12 months, it has begun to see significant explosions in applications and products coming to the mass market. Recently, these applications have included products serving markets such as personal health, fitness, and location awareness. The incorporation of BTv4.0 into a deluge of tablet and smartphone hardware and operating systems offers a multitude of options for designers. They are able to create applications that communicate via BLE to mobile devices running apps providing gateway connectivity to the Internet. According to a Bluetooth Special Interest Group (SIG) press release, “Since the introduction of the iPhone 4s in 2011, Apple methodically turned almost every one of their devices into Bluetooth Smart Ready hubs. These are ready to connect with the over 250 million Bluetooth Smart ‘appcessories’ shipping in 2013 and nearly a billion expected to ship in 2016.”
The proliferation of BTv4.0 into Internet connected mobile devices is not the only advantage that BLE offers to engineers looking to develop products requiring short range wireless connectivity. BLE as a specification was designed from the ground up to offer significant power consumption benefits over Classic Bluetooth. One of the many design targets was the ability to run BLE applications from a coin cell battery for many months, even years. In order to achieve this level of power consumption, BLE operation is focused on being able to wake up, advertise, accept connection, send small amounts of data, disconnect, and return to sleep mode very quickly. All of this means that BLE is ideally suited for power conscious applications that need to send status, alert, or information data relatively infrequently—making BLE ideal for a variety of sensorbased products, such as devices measuring temperature, weight, and steps taken. (See Figure 1)
These technology features have resonated with the location awareness and asset management sectors. There has been an increasing number of products coming to market that allow you to locate, trace, or track everyday items, such as “Tile” (www.thetileapp.com ) or “StickNFind” (www.sticknfind.com ). These markets and products have led to further developments in location awareness for BLE around the concept of ‘beacons’. Interestingly, ABI Research’s latest press release (www.abiresearch.com/press/apple-just-one-of-many-big-guns-entering-4-billion ) for its quarterly Location Technologies Market Data report provides the following estimate on the indoor location market “...a view towards a $4 billion plus market in 2018.” The report even goes as far as highlighting Apple (iBeacons – iOS7 SDK) and eBay’s (PayPal) support of BLE beacons as a significant contributing factor. Though relatively new, a number of companies have already begun to leverage beacon technology, such as with the PayPal Beacon and Estimote’s Beacon that leverages Apple’s iOS 7 iBeacon. Although retailers are among the first to see revenue streams for implementing this technology, other areas, particularly medical applications, could benefit greatly from beacon technology.
Currently, trying to find your way around a large hospital campus, finding a particular bed, or locating a high-value medical device, such as a patient monitor, can be a challenging and frustrating task. However, the use of BLE-based beacon technology could potentially change that. There have been many attempts to deliver proximity/advertising-type applications via Classic Bluetooth but these have tended to be inflexible, complicated, and costly due to the nature of the legacy Classic Bluetooth specification on broadcasting.
A key attribute that the new BT v4.0 specification brings is the ability for BLE devices to broadcast various advertising modes, including general on-air adverts with no requirement for an actual connection. Without getting into the real technical detail of BLE operation, there exist two main roles for BLE enabled devices: Peripheral and Central roles.
A Peripheral role is considered to be the device that needs the lowest power consumption rates, limited processing capability, and simply provides the status or information of its connected sensor, e.g., a temperature gauge. The purpose of the device is to stay in sleep mode as long as possible. Its priority is saving battery power and only waking to send its data infrequently to a Central role device. Central mode devices are expected to have significantly greater processing and power abilities and do the bulk of the “work” from a BLE perspective. In current BLE applications, this Central mode device is a gateway, smartphone, or tablet. This enables the user to benefit from applications running on the Central devices that can alert, update, or trigger web services, such as open a URL, from the data payload of the BLE Peripheral. (See Figure 2)
The advertising capabilities of the Peripheral device in BLE are the key to understanding how BLE-enabled beacons could provide significant advantages against the incumbent indoor location techniques in medical applications. There are several different types of BLE advertisements specified by the Bluetooth SIG.
ADV_NONCONN_IND: This is a broadcast of a small amount of data (maximum of 27 bytes of your data). The device will broadcast only and can’t connect to other BLE devices.
ADV_DISCOVER_IND: Similar to the above, except BLE devices that have the ability to detect and scan a device in this mode can request an additional small payload of data, still without an actual connection.
ADV_IND: All the above but now available for a full BLE connection.
ADV_DIRECT_IND: This enables previously bonded devices to reconnect quickly.
The first two options listed above make exploring BLEenabled beacons for medical use cases so intriguing. It means that small, extremely low-power devices can be configured to simply broadcast their data payload, and do so for many months, or even years. The content of these payloads can be configured differently for a variety of applications for beacons in a medical setting, as illustrated in Figure 3.
The data could be the serial number, manufacturer ID, device type, and wireless signal strength of an expensive patient monitor. This would enable a form of “proximity” location to a specific device based on what it is, and signal strength to help calculate your approximate location to that device.
The advert data configured with generic location information such as patient room number, medical area and/or floor level. This allows “indoor location/mapping” for patients, visitors, or doctors to navigate around a medical facility utilizing an application on a smartphone or tablet.
A final interesting concept that Apple has enabled within iOS7 is that of “geofencing” with BLE adverts. As seen with GPS-style tracking devices, configuration parameters can be provided for a specific area or range, and flag an alert if movement has occurred outside that area. For example, a BLE beacon could be implemented into a wristband worn by an Alzheimer’s patient and configured for a specific area. The patient’s movement outside of the area could trigger an alarm on a nurse’s smartphone or tablet. Alternatively, the beacons could be positioned on patient monitors or infusion pumps with movement alarms sent via central BLE/WiFi gateway to the Internet and, therefore, enabling monitoring from anywhere around the globe.
Tracking Products Indoors
Traditionally, there are several different approaches to indoor location of assets in a medical environment. These can range from the use of RFID tags, utilization of enhanced 802.11 infrastructure techniques, and hybrid methodologies that combine 802.11 with active RFID tags. The key potential advantages of BLE-based beacons versus the current offerings are:
Power Consumption: BLE beacons can run on coin cell batteries for up to two years, depending on application requirements.
Physical Size: The size of the beacon is mainly dictated by the power source used, utilizing a standard CR2032 coin cell, with a nominal diameter of 20mm.
Cost: BLE beacons are relatively inexpensive offerings that don’t need a complicated Bill of Materials outside of the BLE silicon, battery, housing, etc. Commercially available pre-orders of consumer beacons are in the $25 to $30 range at this early adoption stage.
Interoperability with smartphones and tablets: BLE is in, or due to be implemented into, virtually every new smartphone (ABI Research puts this figure at 50% for smartphones in 2013) and tablet hardware with current operating system support from iOS, Android, Linux, and Windows 8. An additional element is the in-built nature of the backhaul connectivity (cellular) provided by smartphones for BLE data to the cloud via applications. The smartphone can be utilizing BLE beacon information in the background and react to the data itself, pushing information to the Internet as needed for storage or analysis.
Configurable Output Power: BLE devices can have a relative, configurable range based on the TX output power of the beacon itself, effectively devices can be configured to only be able to broadcast inches to more than 50 meters. This allows RSSI information to be calculated to provide effective location of the device at various distances.
There are many short-range wireless technologies available in the medical market today and each has its place, based on use case and application requirements. A combination of WiFi and RFID has traditionally been the major wireless system of choice for hospitals looking for indoor location of medical assets and people. A key benefit is the ability to leverage the high level of existing WiFi infrastructure within a hospital currently being utilized for many other network tasks.
The medical sector is not one for hasty change and wholesale adoption of new wireless technologies overnight and so this is not expected to change in the short term. BLE beacons do however offer tantalizing glimpses of what could be for indoor location and asset management within a medical setting. This article focuses solely on the possibilities for a new wireless player to enter this space—offering small, battery-operated beacons that can be used in large numbers inexpensively, providing greater flexibility for enhanced medical device and patient location awareness. The anticipated growth of BLE beacon use in the retail and consumer sectors should be followed closely with an eye on leveraging best practices and applications for medical use.
This article was written by Jonathan Kaye, Product Manager, Laird Technologies, Wooburn Green, UK. For more information, Click Here .